[Fuchsia] Support scroll_*_physical_pixel fields (flutter/engine#34325)

* [WIP][Fuchsia] Support scroll_physical_pixel fields

* add test

* update

* update

* update

* update

* update

* update

* update

* update

* use scroll_delta instead of pan

* use kMouse

* use kMouse

* Update shell/platform/fuchsia/flutter/pointer_delegate.cc

Co-authored-by: Tong Mu <dkwingsmt@users.noreply.github.com>

* Update shell/platform/fuchsia/flutter/pointer_delegate.cc

Co-authored-by: Callum Moffat <smartercallum@gmail.com>

* format

Co-authored-by: Tong Mu <dkwingsmt@users.noreply.github.com>
Co-authored-by: Callum Moffat <smartercallum@gmail.com>

engine/src/flutter/shell/platform/fuchsia/flutter/pointer_delegate.cc

@@ -287,22 +287,40 @@ flutter::PointerData CreateMouseDraft(const fup_MouseEvent& event,
     ptr.buttons = flutter_buttons;
   }
 
-  // Fuchsia currently provides scroll data in "ticks", not physical pixels.
-  // However, Flutter expects scroll data in physical pixels. To compensate for
-  // lack of guidance, we make up a "reasonable amount".
-  // TODO(fxbug.dev/85388): Replace with physical pixel scroll.
+  // Fuchsia previously only provided scroll data in "ticks", not physical
+  // pixels. On legacy platforms, since Flutter expects scroll data in physical
+  // pixels, to compensate for lack of guidance, we make up a "reasonable
+  // amount".
+  // TODO(fxbug.dev/103443): Remove the tick based scrolling after the
+  // transition.
   const int kScrollOffsetMultiplier = 20;
 
-  if (sample.has_scroll_v()) {
-    ptr.signal_kind = flutter::PointerData::SignalKind::kScroll;
-    double dy = -sample.scroll_v() * kScrollOffsetMultiplier;  // logical amount
-    ptr.scroll_delta_y = dy;  // Not yet physical; adjusted in Platform View.
+  double dy = 0;
+  double dx = 0;
+  bool is_scroll = false;
+
+  if (sample.has_scroll_v_physical_pixel()) {
+    dy = -sample.scroll_v_physical_pixel();
+    is_scroll = true;
+  } else if (sample.has_scroll_v()) {
+    dy = -sample.scroll_v() *
+         kScrollOffsetMultiplier;  // logical amount, not yet physical; adjusted
+                                   // in Platform View.
+    is_scroll = true;
   }
 
-  if (sample.has_scroll_h()) {
+  if (sample.has_scroll_h_physical_pixel()) {
+    dx = sample.scroll_h_physical_pixel();
+    is_scroll = true;
+  } else if (sample.has_scroll_h()) {
+    dx = sample.scroll_h() * kScrollOffsetMultiplier;  // logical amount
+    is_scroll = true;
+  }
+
+  if (is_scroll) {
     ptr.signal_kind = flutter::PointerData::SignalKind::kScroll;
-    double dx = sample.scroll_h() * kScrollOffsetMultiplier;  // logical amount
-    ptr.scroll_delta_x = dx;  // Not yet physical; adjusted in Platform View.
+    ptr.scroll_delta_y = dy;
+    ptr.scroll_delta_x = dx;
   }
 
   return ptr;

engine/src/flutter/shell/platform/fuchsia/flutter/pointer_delegate_unittests.cc

@@ -30,6 +30,7 @@ using fup_TouchPointerSample = fuchsia::ui::pointer::TouchPointerSample;
 using fup_TouchResponse = fuchsia::ui::pointer::TouchResponse;
 using fup_TouchResponseType = fuchsia::ui::pointer::TouchResponseType;
 using fup_ViewParameters = fuchsia::ui::pointer::ViewParameters;
+using fup_MouseEvent = fuchsia::ui::pointer::MouseEvent;
 
 constexpr std::array<std::array<float, 2>, 2> kRect = {{{0, 0}, {20, 20}}};
 constexpr std::array<float, 9> kIdentity = {1, 0, 0, 0, 1, 0, 0, 0, 1};
@@ -37,6 +38,11 @@ constexpr fup_TouchIxnId kIxnOne = {.device_id = 1u,
                                     .pointer_id = 1u,
                                     .interaction_id = 2u};
 
+constexpr uint32_t kMouseDeviceId = 123;
+constexpr std::array<int64_t, 2> kNoScrollInPhysicalPixelDelta = {0, 0};
+const bool kNotPrecisionScroll = false;
+const bool kPrecisionScroll = true;
+
 // Fixture to exercise Flutter runner's implementation for
 // fuchsia.ui.pointer.TouchSource.
 class PointerDelegateTest : public ::testing::Test {
@@ -676,4 +682,163 @@ TEST_F(PointerDelegateTest, Protocol_PointersAreIndependent) {
   pointers = {};
 }
 
+TEST_F(PointerDelegateTest, MouseWheel_TickBased) {
+  std::optional<std::vector<flutter::PointerData>> pointers;
+  pointer_delegate_->WatchLoop(
+      [&pointers](std::vector<flutter::PointerData> events) {
+        pointers = std::move(events);
+      });
+  RunLoopUntilIdle();  // Server gets watch call.
+
+  std::vector<fup_MouseEvent> events =
+      MouseEventBuilder()
+          .AddTime(1111789u)
+          .AddViewParameters(kRect, kRect, kIdentity)
+          .AddSample(kMouseDeviceId, {10.f, 10.f}, {}, {0, 1},
+                     kNoScrollInPhysicalPixelDelta, kNotPrecisionScroll)
+          .AddMouseDeviceInfo(kMouseDeviceId, {0, 1, 2})
+          .BuildAsVector();
+  mouse_source_->ScheduleCallback(std::move(events));
+  RunLoopUntilIdle();
+
+  ASSERT_TRUE(pointers.has_value());
+  ASSERT_EQ(pointers.value().size(), 1u);
+  EXPECT_EQ(pointers.value()[0].change, flutter::PointerData::Change::kHover);
+  EXPECT_EQ(pointers.value()[0].signal_kind,
+            flutter::PointerData::SignalKind::kScroll);
+  EXPECT_EQ(pointers.value()[0].kind, flutter::PointerData::DeviceKind::kMouse);
+  EXPECT_EQ(pointers.value()[0].buttons, 0);
+  EXPECT_EQ(pointers.value()[0].scroll_delta_x, 0);
+  EXPECT_EQ(pointers.value()[0].scroll_delta_y, -20);
+  pointers = {};
+
+  // receive a horizontal scroll
+  events = MouseEventBuilder()
+               .AddTime(1111789u)
+               .AddViewParameters(kRect, kRect, kIdentity)
+               .AddSample(kMouseDeviceId, {10.f, 10.f}, {}, {1, 0},
+                          kNoScrollInPhysicalPixelDelta, kNotPrecisionScroll)
+               .AddMouseDeviceInfo(kMouseDeviceId, {0, 1, 2})
+               .BuildAsVector();
+  mouse_source_->ScheduleCallback(std::move(events));
+  RunLoopUntilIdle();
+
+  ASSERT_TRUE(pointers.has_value());
+  ASSERT_EQ(pointers.value().size(), 1u);
+  EXPECT_EQ(pointers.value()[0].change, flutter::PointerData::Change::kHover);
+  EXPECT_EQ(pointers.value()[0].signal_kind,
+            flutter::PointerData::SignalKind::kScroll);
+  EXPECT_EQ(pointers.value()[0].kind, flutter::PointerData::DeviceKind::kMouse);
+  EXPECT_EQ(pointers.value()[0].buttons, 0);
+  EXPECT_EQ(pointers.value()[0].scroll_delta_x, 20);
+  EXPECT_EQ(pointers.value()[0].scroll_delta_y, 0);
+  pointers = {};
+}
+
+TEST_F(PointerDelegateTest, MouseWheel_PixelBased) {
+  std::optional<std::vector<flutter::PointerData>> pointers;
+  pointer_delegate_->WatchLoop(
+      [&pointers](std::vector<flutter::PointerData> events) {
+        pointers = std::move(events);
+      });
+  RunLoopUntilIdle();  // Server gets watch call.
+
+  std::vector<fup_MouseEvent> events =
+      MouseEventBuilder()
+          .AddTime(1111789u)
+          .AddViewParameters(kRect, kRect, kIdentity)
+          .AddSample(kMouseDeviceId, {10.f, 10.f}, {}, {0, 1}, {0, 120},
+                     kNotPrecisionScroll)
+          .AddMouseDeviceInfo(kMouseDeviceId, {0, 1, 2})
+          .BuildAsVector();
+  mouse_source_->ScheduleCallback(std::move(events));
+  RunLoopUntilIdle();
+
+  ASSERT_TRUE(pointers.has_value());
+  ASSERT_EQ(pointers.value().size(), 1u);
+  EXPECT_EQ(pointers.value()[0].change, flutter::PointerData::Change::kHover);
+  EXPECT_EQ(pointers.value()[0].signal_kind,
+            flutter::PointerData::SignalKind::kScroll);
+  EXPECT_EQ(pointers.value()[0].kind, flutter::PointerData::DeviceKind::kMouse);
+  EXPECT_EQ(pointers.value()[0].buttons, 0);
+  EXPECT_EQ(pointers.value()[0].scroll_delta_x, 0);
+  EXPECT_EQ(pointers.value()[0].scroll_delta_y, -120);
+  pointers = {};
+
+  // receive a horizontal scroll
+  events = MouseEventBuilder()
+               .AddTime(1111789u)
+               .AddViewParameters(kRect, kRect, kIdentity)
+               .AddSample(kMouseDeviceId, {10.f, 10.f}, {}, {1, 0}, {120, 0},
+                          kNotPrecisionScroll)
+               .AddMouseDeviceInfo(kMouseDeviceId, {0, 1, 2})
+               .BuildAsVector();
+  mouse_source_->ScheduleCallback(std::move(events));
+  RunLoopUntilIdle();
+
+  ASSERT_TRUE(pointers.has_value());
+  ASSERT_EQ(pointers.value().size(), 1u);
+  EXPECT_EQ(pointers.value()[0].change, flutter::PointerData::Change::kHover);
+  EXPECT_EQ(pointers.value()[0].signal_kind,
+            flutter::PointerData::SignalKind::kScroll);
+  EXPECT_EQ(pointers.value()[0].kind, flutter::PointerData::DeviceKind::kMouse);
+  EXPECT_EQ(pointers.value()[0].buttons, 0);
+  EXPECT_EQ(pointers.value()[0].scroll_delta_x, 120);
+  EXPECT_EQ(pointers.value()[0].scroll_delta_y, 0);
+  pointers = {};
+}
+
+TEST_F(PointerDelegateTest, MouseWheel_TouchpadPixelBased) {
+  std::optional<std::vector<flutter::PointerData>> pointers;
+  pointer_delegate_->WatchLoop(
+      [&pointers](std::vector<flutter::PointerData> events) {
+        pointers = std::move(events);
+      });
+  RunLoopUntilIdle();  // Server gets watch call.
+
+  std::vector<fup_MouseEvent> events =
+      MouseEventBuilder()
+          .AddTime(1111789u)
+          .AddViewParameters(kRect, kRect, kIdentity)
+          .AddSample(kMouseDeviceId, {10.f, 10.f}, {}, {0, 1}, {0, 120},
+                     kPrecisionScroll)
+          .AddMouseDeviceInfo(kMouseDeviceId, {0, 1, 2})
+          .BuildAsVector();
+  mouse_source_->ScheduleCallback(std::move(events));
+  RunLoopUntilIdle();
+
+  ASSERT_TRUE(pointers.has_value());
+  ASSERT_EQ(pointers.value().size(), 1u);
+  EXPECT_EQ(pointers.value()[0].change, flutter::PointerData::Change::kHover);
+  EXPECT_EQ(pointers.value()[0].signal_kind,
+            flutter::PointerData::SignalKind::kScroll);
+  EXPECT_EQ(pointers.value()[0].kind, flutter::PointerData::DeviceKind::kMouse);
+  EXPECT_EQ(pointers.value()[0].buttons, 0);
+  EXPECT_EQ(pointers.value()[0].scroll_delta_x, 0);
+  EXPECT_EQ(pointers.value()[0].scroll_delta_y, -120);
+  pointers = {};
+
+  // receive a horizontal scroll
+  events = MouseEventBuilder()
+               .AddTime(1111789u)
+               .AddViewParameters(kRect, kRect, kIdentity)
+               .AddSample(kMouseDeviceId, {10.f, 10.f}, {}, {1, 0}, {120, 0},
+                          kPrecisionScroll)
+               .AddMouseDeviceInfo(kMouseDeviceId, {0, 1, 2})
+               .BuildAsVector();
+  mouse_source_->ScheduleCallback(std::move(events));
+  RunLoopUntilIdle();
+
+  ASSERT_TRUE(pointers.has_value());
+  ASSERT_EQ(pointers.value().size(), 1u);
+  EXPECT_EQ(pointers.value()[0].change, flutter::PointerData::Change::kHover);
+  EXPECT_EQ(pointers.value()[0].signal_kind,
+            flutter::PointerData::SignalKind::kScroll);
+  EXPECT_EQ(pointers.value()[0].kind, flutter::PointerData::DeviceKind::kMouse);
+  EXPECT_EQ(pointers.value()[0].buttons, 0);
+  EXPECT_EQ(pointers.value()[0].scroll_delta_x, 120);
+  EXPECT_EQ(pointers.value()[0].scroll_delta_y, 0);
+  pointers = {};
+}
+
 }  // namespace flutter_runner::testing

engine/src/flutter/shell/platform/fuchsia/flutter/tests/pointer_event_utility.cc

@@ -12,6 +12,30 @@ using fup_TouchIxnId = fuchsia::ui::pointer::TouchInteractionId;
 using fup_TouchIxnResult = fuchsia::ui::pointer::TouchInteractionResult;
 using fup_TouchPointerSample = fuchsia::ui::pointer::TouchPointerSample;
 using fup_ViewParameters = fuchsia::ui::pointer::ViewParameters;
+using fup_MouseEvent = fuchsia::ui::pointer::MouseEvent;
+using fup_MousePointerSample = fuchsia::ui::pointer::MousePointerSample;
+using fup_MouseDeviceInfo = fuchsia::ui::pointer::MouseDeviceInfo;
+
+namespace {
+
+fup_ViewParameters CreateViewParameters(
+    std::array<std::array<float, 2>, 2> view,
+    std::array<std::array<float, 2>, 2> viewport,
+    std::array<float, 9> transform) {
+  fup_ViewParameters params;
+  fuchsia::ui::pointer::Rectangle view_rect;
+  view_rect.min = view[0];
+  view_rect.max = view[1];
+  params.view = view_rect;
+  fuchsia::ui::pointer::Rectangle viewport_rect;
+  viewport_rect.min = viewport[0];
+  viewport_rect.max = viewport[1];
+  params.viewport = viewport_rect;
+  params.viewport_to_view_transform = transform;
+  return params;
+}
+
+}  // namespace
 
 TouchEventBuilder TouchEventBuilder::New() {
   return TouchEventBuilder();
@@ -36,16 +60,8 @@ TouchEventBuilder& TouchEventBuilder::AddViewParameters(
     std::array<std::array<float, 2>, 2> view,
     std::array<std::array<float, 2>, 2> viewport,
     std::array<float, 9> transform) {
-  params_ = std::make_optional<fup_ViewParameters>();
-  fuchsia::ui::pointer::Rectangle view_rect;
-  view_rect.min = view[0];
-  view_rect.max = view[1];
-  params_->view = view_rect;
-  fuchsia::ui::pointer::Rectangle viewport_rect;
-  viewport_rect.min = viewport[0];
-  viewport_rect.max = viewport[1];
-  params_->viewport = viewport_rect;
-  params_->viewport_to_view_transform = transform;
+  params_ = CreateViewParameters(std::move(view), std::move(viewport),
+                                 std::move(transform));
   return *this;
 }
 
@@ -77,4 +93,84 @@ std::vector<fup_TouchEvent> TouchEventBuilder::BuildAsVector() {
   return events;
 }
 
+MouseEventBuilder MouseEventBuilder::New() {
+  return MouseEventBuilder();
+}
+
+MouseEventBuilder& MouseEventBuilder::AddTime(zx_time_t time) {
+  time_ = time;
+  return *this;
+}
+
+MouseEventBuilder& MouseEventBuilder::AddSample(
+    uint32_t id,
+    std::array<float, 2> position,
+    std::vector<uint8_t> pressed_buttons,
+    std::array<int64_t, 2> scroll,
+    std::array<int64_t, 2> scroll_in_physical_pixel,
+    bool is_precision_scroll) {
+  sample_ = std::make_optional<fup_MousePointerSample>();
+  sample_->set_device_id(id);
+  if (!pressed_buttons.empty()) {
+    sample_->set_pressed_buttons(pressed_buttons);
+  }
+  sample_->set_position_in_viewport(position);
+  if (scroll[0] != 0) {
+    sample_->set_scroll_h(scroll[0]);
+  }
+  if (scroll[1] != 0) {
+    sample_->set_scroll_v(scroll[1]);
+  }
+  if (scroll_in_physical_pixel[0] != 0) {
+    sample_->set_scroll_h_physical_pixel(scroll_in_physical_pixel[0]);
+  }
+  if (scroll_in_physical_pixel[1] != 0) {
+    sample_->set_scroll_v_physical_pixel(scroll_in_physical_pixel[1]);
+  }
+  sample_->set_is_precision_scroll(is_precision_scroll);
+  return *this;
+}
+
+MouseEventBuilder& MouseEventBuilder::AddViewParameters(
+    std::array<std::array<float, 2>, 2> view,
+    std::array<std::array<float, 2>, 2> viewport,
+    std::array<float, 9> transform) {
+  params_ = CreateViewParameters(std::move(view), std::move(viewport),
+                                 std::move(transform));
+  return *this;
+}
+
+MouseEventBuilder& MouseEventBuilder::AddMouseDeviceInfo(
+    uint32_t id,
+    std::vector<uint8_t> buttons) {
+  device_info_ = std::make_optional<fup_MouseDeviceInfo>();
+  device_info_->set_id(id);
+  device_info_->set_buttons(buttons);
+  return *this;
+}
+
+fup_MouseEvent MouseEventBuilder::Build() {
+  fup_MouseEvent event;
+  if (time_) {
+    event.set_timestamp(time_.value());
+  }
+  if (params_) {
+    event.set_view_parameters(std::move(params_.value()));
+  }
+  if (sample_) {
+    event.set_pointer_sample(std::move(sample_.value()));
+  }
+  if (device_info_) {
+    event.set_device_info(std::move(device_info_.value()));
+  }
+  event.set_trace_flow_id(123);
+  return event;
+}
+
+std::vector<fup_MouseEvent> MouseEventBuilder::BuildAsVector() {
+  std::vector<fup_MouseEvent> events;
+  events.emplace_back(Build());
+  return events;
+}
+
 }  // namespace flutter_runner::testing

engine/src/flutter/shell/platform/fuchsia/flutter/tests/pointer_event_utility.h

@@ -40,6 +40,34 @@ class TouchEventBuilder {
   std::optional<fuchsia::ui::pointer::TouchInteractionResult> result_;
 };
 
+// A helper class for crafting a fuchsia.ui.pointer.MouseEventBuilder table.
+class MouseEventBuilder {
+ public:
+  static MouseEventBuilder New();
+
+  MouseEventBuilder& AddTime(zx_time_t time);
+  MouseEventBuilder& AddSample(uint32_t id,
+                               std::array<float, 2> position,
+                               std::vector<uint8_t> pressed_buttons,
+                               std::array<int64_t, 2> scroll,
+                               std::array<int64_t, 2> scroll_in_physical_pixel,
+                               bool is_precision_scroll);
+  MouseEventBuilder& AddViewParameters(
+      std::array<std::array<float, 2>, 2> view,
+      std::array<std::array<float, 2>, 2> viewport,
+      std::array<float, 9> transform);
+  MouseEventBuilder& AddMouseDeviceInfo(uint32_t id,
+                                        std::vector<uint8_t> buttons);
+  fuchsia::ui::pointer::MouseEvent Build();
+  std::vector<fuchsia::ui::pointer::MouseEvent> BuildAsVector();
+
+ private:
+  std::optional<zx_time_t> time_;
+  std::optional<fuchsia::ui::pointer::MousePointerSample> sample_;
+  std::optional<fuchsia::ui::pointer::ViewParameters> params_;
+  std::optional<fuchsia::ui::pointer::MouseDeviceInfo> device_info_;
+};
+
 }  // namespace flutter_runner::testing
 
 #endif  // FLUTTER_SHELL_PLATFORM_FUCHSIA_TESTS_POINTER_EVENT_UTILITY_H_